1. Field of the Invention
The present invention relates to a gripper mechanism for gripping and feeding separate elongate strips such as slide fastener stringers in an apparatus for finishing slide fasteners.
2. Description of the Prior Art
One typical gripper mechanism for feeding slide fastener stringers simultaneously over a given distance in timed relation to the operation of a positioning device is disclosed in Japanese Patent Publication No. 49-44243 published on Nov. 27, 1974. The disclosed gripper mechanism includes a pair of grippers for gripping the leading ends of a pair of elongate slide fastener stringers after certain components have been attached to the stringers and then for pulling the slide fastener stringers, along a feed path for the prescribed interval. In response to detection by a positioning device of the slide fastener stringers having travelled over the desired interval, the grippers are stopped, and the slide fastener stringers are cut off across element-free spaces or gaps thereof into individual stringer lengths which are then fed to a discharge position.
Since the slide fastener stringers are composed of woven or knit stringer tapes of textile material, they often tend to be stretched longitudinally under traction when subjected to changes in temperature and moisture while the stringers are being pulled in a finishing process. In particular, slide fastener stringers of elongate dimensions are liable to have different lengths while they are being processed. When the differently stretched stringers are detected by the chain positioning device and stopped at the same time, the element-free tape areas thereof where the stringers are to be cut off are positioned out of transverse alignment with each other. Therefore, the severed tape edges would not be equally spaced from the terminal coupling elements of the following stringers, and hence the terminal coupling elements would be transversely misaligned. For this reason, various fastener components such as end stops, pins and boxes could not be attached to the stringers at proper positions thereon.